The invention relates to carriers for transporting a textile bobbin, and more particularly to carriers of the type having a generally flat disk-like base and a pin or post upstanding centrally from the base for use in supporting and transporting textile yarn bobbins and tubes.
Transport systems in which carriers circulate on transport paths formed by rail-like transport channels for the base plates of the carriers are known for supporting and transporting textile cops, for example, as disclosed by Japanese Patent Disclosure A 52-25139, A pin or post extends from the disk-like base plate of each carrier and is telescopically received within the hollow end of the bobbin in order to support and hold it in upstanding disposition on the base plate. The outside diameter of the pin or post is slightly smaller than the inside diameter of the tube of the bobbin to be transported, to assure problem-free mounting and doffing of the bobbin,
Carriers of this basic type are used for automatic bobbin winders, in which the carriers circulate in a transport loop, as described for example by German Patent DE 32 35 442 A1. The cops remain mounted on these carriers for the duration of the time they spend in processing stations of the winder and over long portions of the transport path system, In order to produce the necessary rotary motion of the cops in a cop preparation station, this German patent proposes that rotary motion of the carrier be resisted by means of retaining elements, while driven friction wheels placed at the base of the cop transmit the desired rotary motion directly to the cop. Disadvantageously, any windings that may be present at the base of the cop are wedged in place by the friction wheel and hence cannot be loosened.
By comparison, driving the carriers themselves has the advantage that the drive elements have no contact with the cop. To assure that the cop will be carried along in this transfer of drive motion, German patent DE 40 16 466 A1 proposed providing the pin or post with an elastic element whose outside diameter in a relaxed unstressed state is greater than the inside diameter of the textile bobbin tube, yet is sufficiently compressible to enable the pin or post to receive the base end of the tube. Although the frictional gripping force attained in this way does assure satisfactory driving of the cop when the carrier is driven and also assures that no shifting of the bobbin on the pin or post occurs if vertical forces are applied to the cop, mounting the bobbin on the pin or post and doffing it requires the exertion of relatively strong forces. Gripper devices used for this purpose must therefore exert relatively significant pressing forces, particularly if tolerances in production of the bobbin tube cause the inside diameter of some tubes to be below a standard size.